Ultrasound-guided regional neuraxial anesthesia has been described in the anesthesia literature since 1971. The literature reports a reduction in the number of attempts, need for repositioning, and interspaces accessed compared with landmark-guided spinal or epidural anesthesia.[7,8] The use of bedside ultrasound to help guide difficult lumbar punctures has spread to the emergency room, ICU, and the hospital wards over the last 7 years. Observational studies have demonstrated that lumbar landmarks can be correctly identified using ultrasound about 76% of the time when they are difficult to palpate.[2,3,9]The technique for ultrasound-guided lumbar punctures typically utilizes a high-frequency linear ultrasound probe, however, a low-frequency curvilinear probe may be needed in morbidly obese or markedly edematous patients when the spinal structures are too deep. Initially, a transverse view is used to identify the L3 or L4 posterior spinous process and center this landmark on the monitor. The bony spinous process will appear as a convex hyperechoic structure which creates a “bony shadow” behind it. Marks are made on the skin cephalad and caudad to the probe in its midportion. Two spinous processes should be identified to assure that the midline of the spine is correctly demarcated.
The probe is then turned to a longitudinal orientation in order to identify the interspinous space. The probe should follow the midline of the spine to identify two adjacent posterior spinous processes. Using a linear array probe, adjacent spinous processes can usually be identified in the same monitor image. The center of the interspinous space can then be identified and demarcated using a mark on the skin on each side of the probe. The lines designating the midline and the interspinous space can then be connected to make a “+” sign on the back where the middle represent the needle insertion site. A surgical marking pen is ideal for skin marking since it will not rub off during aseptic preparation of the skin.
It is essential that exact patient positioning is maintained between the ultrasound determination of landmarks and the performance of the lumbar puncture. Patient position changes can alter the relationship between the skin markings and the underlying bony landmarks.
Obviously, there is a learning curve to every technique. However, emergency physicians, intensivists, and hospitalists should consider the use of bedside ultrasound to assist with lumbar punctures when the lumbar landmarks are difficult to palpate.
Joseph Esherick, MD, FAAFP is the Associate Director of Medicine and the Medical ICU Director at the Ventura County Medical Center in Ventura, California. He is also an Associate Clinical Professor of Family Medicine at The David Geffen School of Medicine at UCLA. He received his medical degree from Yale University School of Medicine, New Haven, Connecticut, and completed a family practice residency at the Ventura County Medical Center, Ventura, California. He is board certified in family medicine and the author of the Tarascon Primary Care Pocketbook and the Tarascon Hospital Medicine Pocketbook. He instructs the Hospitalist Procedures course for the National Procedures Institute and is an editorial board member for Tarascon Publishing and for Elsevier’s First Consult.
Dr. Esherick is the author of some of Tarascon Publishing’s best-selling titles including:
The recently published Tarascon Medical Procedures Pocketbook, Tarascon Hospital Medicine Pocketbook and Tarascon Primary Care Pocketbook. Both titles are available in print and mobile (iPhone, Android and Blackberry).
___________________________________________________________ Quincke HI (1891). Verhandlungen des Congresses für Innere Medizin, Zehnter Congress, Wiesbaden. 10. pp. 321–331.  Stiffler KA, Jwayyed S, Wilber ST, Robinson A. The use of ultrasound to identify pertinent landmarks for lumbar puncture. Am J Emerg Med 2007; 25(3): 331-4.  Peterson MA, Abele J. Bedside ultrasound for difficult lumbar puncture. J Emerg Med 2005; 28(2): 197-200.  Ferre RM, Sweeney TW. Emergency physicians can easily obtain ultrasound images of anatomical landmarks relevant to lumbar puncture. Am J Emerg Med 2007; 25(3): 291-6.  Nomura JT et al. A Randomized Controlled Trial of Ultrasound-Assisted Lumbar Puncture. J Ultrasound Med 2007; 26: 1341-1348.  Bogin IN, Stulin ID. [Application of the method of 2-dimensional echospondylography for determining landmarks in lumbar punctures]. Zh Nevropatol Psikhiatr Im S S Korsakova 1971; 71(12): 1810-1.  Grau T, Leipold, Conradi, R, Martin, E, Motsch, J. Efficacy of Ultrasound imaging in Obstetric Epidural Anesthesia. Journal of Clinical Anesthesia 2002; 14: 169-75.  Grau T, Leipold RW, Conradi R, Martin E, Motsch J. Ultrasound imaging facilitates localization of the epidural space during combined spinal and epidural anesthesia. Reg Anesth Pain Med 2001; 26(1): 64-7.  Strony R. Ultrasound-assisted lumbar puncture in obese patients. Crit Care Clin. 2010 Oct; 26(4): 661-4.